diff --git a/eos/base/election.py b/eos/base/election.py
index 1f98ed6..d018107 100644
--- a/eos/base/election.py
+++ b/eos/base/election.py
@@ -40,8 +40,8 @@ class Ballot(EmbeddedObject):
 	def deaudit(self):
 		encrypted_answers_deaudit = EosList()
 		
-		for i in range(len(self.encrypted_answers)):
-			encrypted_answers_deaudit.append(self.encrypted_answers[i].deaudit())
+		for encrypted_answer in self.encrypted_answers:
+			encrypted_answers_deaudit.append(encrypted_answer.deaudit())
 		
 		return Ballot(encrypted_answers=encrypted_answers_deaudit, election_id=self.election_id, election_hash=self.election_hash)
 
@@ -106,7 +106,7 @@ class ApprovalQuestion(Question):
 	max_choices = IntField()
 	
 	def pretty_answer(self, answer):
-		return ', '.join([self.choices[answer.choices[i]] for i in range(len(answer.choices))])
+		return ', '.join([self.choices[choice] for choice in answer.choices])
 
 class ApprovalAnswer(Answer):
 	choices = ListField(IntField())
@@ -117,7 +117,7 @@ class PreferentialQuestion(Question):
 	max_choices = IntField()
 	
 	def pretty_answer(self, answer):
-		return ', '.join([self.choices[answer.choices[i]] for i in range(len(answer.choices))])
+		return ', '.join([self.choices[choice] for choice in answer.choices])
 
 class PreferentialAnswer(Answer):
 	choices = ListField(IntField())
diff --git a/eos/base/workflow.py b/eos/base/workflow.py
index a801794..46280d4 100644
--- a/eos/base/workflow.py
+++ b/eos/base/workflow.py
@@ -103,8 +103,7 @@ class Workflow(EmbeddedObject):
 	
 	def get_tasks(self, descriptor):
 		#yield from (task for task in self.tasks if task.satisfies(descriptor))
-		for i in range(len(self.tasks)):
-			task = self.tasks[i]
+		for task in self.tasks:
 			if task.satisfies(descriptor):
 				yield task
 	
@@ -141,10 +140,10 @@ class TaskDecryptVotes(WorkflowTask):
 			if len(voter.votes) > 0:
 				vote = voter.votes[-1]
 				ballot = vote.ballot
-				for i in range(len(ballot.encrypted_answers)):
-					plaintexts, answer = ballot.encrypted_answers[i].decrypt()
-					election.results[i].plaintexts.append(plaintexts)
-					election.results[i].answers.append(answer)
+				for q_num in range(len(ballot.encrypted_answers)):
+					plaintexts, answer = ballot.encrypted_answers[q_num].decrypt()
+					election.results[q_num].plaintexts.append(plaintexts)
+					election.results[q_num].answers.append(answer)
 		
 		self.exit()
 
diff --git a/eos/psr/bitstream.py b/eos/psr/bitstream.py
index 24bf244..2be2498 100644
--- a/eos/psr/bitstream.py
+++ b/eos/psr/bitstream.py
@@ -137,8 +137,8 @@ class BitStream(EosObject):
 	@classmethod
 	def unmap(cls, value, func, block_size):
 		bs = cls()
-		for i in range(len(value)):
-			bs.write(func(value[i]), block_size)
+		for item in value:
+			bs.write(func(item), block_size)
 		bs.seek(0)
 		return bs
 	
diff --git a/eos/psr/election.py b/eos/psr/election.py
index 5865dec..8b4504b 100644
--- a/eos/psr/election.py
+++ b/eos/psr/election.py
@@ -40,7 +40,7 @@ class BlockEncryptedAnswer(EncryptedAnswer):
 		if sk is None:
 			sk = self.recurse_parents(PSRElection).sk
 		
-		plaintexts = EosList([sk.decrypt_and_prove(self.blocks[i]) for i in range(len(self.blocks))])
+		plaintexts = EosList([sk.decrypt_and_prove(block) for block in self.blocks])
 		
 		bs = BitStream.unmap(plaintexts, lambda plaintext: plaintext.message, sk.public_key.nbits())
 		m = bs.read_string()
@@ -51,8 +51,8 @@ class BlockEncryptedAnswer(EncryptedAnswer):
 	def deaudit(self):
 		blocks_deaudit = EosList()
 		
-		for i in range(len(self.blocks)):
-			blocks_deaudit.append(self.blocks[i].deaudit())
+		for block in self.blocks:
+			blocks_deaudit.append(block.deaudit())
 		
 		return BlockEncryptedAnswer(blocks=blocks_deaudit)
 
@@ -78,8 +78,8 @@ class MixingTrustee(Trustee):
 		
 		sha = SHA256()
 		trustees = self.recurse_parents(Election).mixing_trustees
-		for i in range(len(trustees)):
-			sha.update_text(EosObject.to_json(MixingTrustee._fields['mixed_questions'].element_field.serialise(trustees[i].mixed_questions[question_num])))
+		for trustee in trustees:
+			sha.update_text(EosObject.to_json(MixingTrustee._fields['mixed_questions'].element_field.serialise(trustee.mixed_questions[question_num])))
 		for i in range(self._instance[1]):
 			sha.update_text(EosObject.to_json(MixingTrustee._fields['response'].element_field.serialise(trustees[i].response[question_num])))
 		return sha.hash_as_bigint()
diff --git a/eos/psr/tests.py b/eos/psr/tests.py
index 6604263..f4c8d49 100644
--- a/eos/psr/tests.py
+++ b/eos/psr/tests.py
@@ -142,9 +142,9 @@ class BlockEGTestCase(EosTestCase):
 	def test_basic(self):
 		pt = BigInt('11010010011111010100101', 2)
 		ct = BitStream(pt).multiple_of(self.sk.public_key.nbits()).map(self.sk.public_key.encrypt, self.sk.public_key.nbits())
-		for i in range(len(ct)):
-			self.assertTrue(ct[i].gamma < self.test_group.p)
-			self.assertTrue(ct[i].delta < self.test_group.p)
+		for ct_block in ct:
+			self.assertTrue(ct_block.gamma < self.test_group.p)
+			self.assertTrue(ct_block.delta < self.test_group.p)
 		m = BitStream.unmap(ct, self.sk.decrypt, self.sk.public_key.nbits()).read()
 		self.assertEqualJSON(pt, m)
 	
@@ -164,13 +164,13 @@ class MixnetTestCase(EosTestCase):
 		
 		# Generate plaintexts
 		pts = []
-		for i in range(4):
+		for _ in range(4):
 			pts.append(sk.public_key.group.random_Zq_element())
 		
 		# Encrypt plaintexts
 		answers = []
-		for i in range(len(pts)):
-			bs = BitStream(pts[i])
+		for pt in pts:
+			bs = BitStream(pt)
 			bs.multiple_of(sk.public_key.nbits())
 			ct = bs.map(sk.public_key.encrypt, sk.public_key.nbits())
 			answers.append(BlockEncryptedAnswer(blocks=ct))
@@ -184,8 +184,8 @@ class MixnetTestCase(EosTestCase):
 			
 			# Decrypt shuffle
 			msgs = []
-			for i in range(len(shuffled_answers)):
-				bs = BitStream.unmap(shuffled_answers[i].blocks, sk.decrypt, sk.public_key.nbits())
+			for shuffled_answer in shuffled_answers:
+				bs = BitStream.unmap(shuffled_answer.blocks, sk.decrypt, sk.public_key.nbits())
 				m = bs.read()
 				msgs.append(m)
 			
@@ -241,7 +241,7 @@ class ElectionTestCase(EosTestCase):
 			voter = Voter(name=['Alice', 'Bob', 'Charlie'][i])
 			election.voters.append(voter)
 		
-		for i in range(3):
+		for _ in range(3):
 			mixing_trustee = InternalMixingTrustee()
 			election.mixing_trustees.append(mixing_trustee)
 		
@@ -339,8 +339,7 @@ class PVSSTestCase(EosTestCase):
 		# IRL: Send hi=F[0] commitments around
 		
 		# Send shares around
-		for i in range(len(setup.participants)):
-			participant = setup.participants[i]
+		for participant in setup.participants:
 			for j in range(len(setup.participants)):
 				other = setup.participants[j]
 				share = participant.get_share_for(j)
@@ -361,7 +360,7 @@ class PVSSTestCase(EosTestCase):
 				# Verify share received by other from participant
 				share_dec = other.shares_received[i]
 				g_share_dec_expected = ONE
-				for k in range(0, setup.threshold):
+				for k in range(setup.threshold):
 					g_share_dec_expected = (g_share_dec_expected * pow(participant.F[k], pow(j + 1, k), setup.group.p)) % setup.group.p
 				if pow(setup.group.g, share_dec, setup.group.p) != g_share_dec_expected:
 					raise Exception('Share not consistent with commitments')
diff --git a/requirements.txt b/requirements.txt
index 27ef854..a4ccf56 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -9,15 +9,16 @@ idna==2.6
 itsdangerous==0.24
 Jinja2==2.10
 MarkupSafe==1.0
-mypy==0.521
+mypy==0.550
 oauthlib==2.0.6
+psutil==5.4.1
 psycopg2==2.7.3.2
 PyExecJS==1.4.1
 pymongo==3.5.1
 requests==2.18.4
 requests-oauthlib==0.8.0
 six==1.10.0
-Transcrypt==3.6.50
-typed-ast==1.0.4
+Transcrypt==3.6.58
+typed-ast==1.1.0
 urllib3==1.22
 Werkzeug==0.12.2